Application for the Reassessment of a Hazardous Substance under ...

Comparison of levels of concern (Table E.1) to the risk quotient in Table E.3 showshigh acute risk to invertebrates in the freshwater environment. The risks to fish andaquatic plants are low. This conclusion is based on Tier 0 modelling of exposure(GENEEC2).To explore risk reduction options, ERMA New Zealand used the AgDrift model toestimate the buffer zone that would reduce exposure through spray drift to aconcentration unlikely to cause acute toxicity. The receiving water was defined as a 30cm deep pond. Spray drift is only one route of exposure by which dichlorvos willcontaminate the aquatic environment, but given the rapid dissipation of dichlorvos itwill be important. The model indicated that even for the lowest application rate (800 gai/ha), a buffer zone > 304 meters is required to reduce the receiving waterconcentration to less than the lowest acute EC/LC 50 .GroundwaterTier 0 modelling of concentrations in groundwater predicts concentrations from 0.00069to 0.0036µg/L. In the EU, 0.1 µg/L is the concentration above which the predictedconcentration is considered to be unacceptable. As this level of concern is not exceededERMA New Zealand considers the risks for groundwater are low.BirdsThe avian toxicity assessment was performed according to ―Risk Assessment to Birdsand Mammals (EFSA 2008)‖. The risk assessment is based on a TER (toxicity-exposureratio) approach. For pesticides in general, mortality is unlikely when TER ≥ 10 (acuterisk). No assessment of chronic risk was made due to the rapid dissipation ofdichlorvos in the environment.Table E.4:Acute avian risk assessment – screening stepScenario Crop 1 IndicatorSpecies 2 LD 503DDD 4 TER 5 valueTrigger1 strawberries Small omnivorous bird 9.18 127.04 0.07